Age-resisting compound for vulcanized rubber



Patented Nov. 5, 1929 UNITED STATES PATENT OFF-ICE MAX H. ZEMMERMANN, F NEWINGTON, NEW HAMPSHIRE, ASSIGNOR, BY MESNE ASSIGNMENTS, 'IO ALBERT C. BURRAGE, JR, 0F IPSWICH, MASSACHUSETTS AGE-BESISTING COMPOUND FOR VULGANIZED RUBBER No Drawing.

This invention relates to vulcanized rubber and to means for preventing the deleterious effects of oxidation or aging thereon.

The eflects of aging upon vulcanized rubber, especially when exposed to the atmosphere and to sunlight,including loss of resiliency, strength and the like,are well known and are frequently attributed to oxidation. Such effects obviously reduce the quality and value of the rubber and are accordingly undesirable.

Accordingly, an object of this invention is to provide a vulcanized rubber which shall be substantially resistant to the effects ofaging or oxidation. Other objects will appear from the following disclosure.

Generically, the invention includes the provision of vulcanized rubber characterized by containing, as the age-resisting or anti-oxidant compound, a substituted nitroso-amine, typified by the form'ula: Y

in which R and R represent alkyl or aryl radicals (or nuclei) which may be alike or unlike and may contain oir be associated with one or more substituents. In the aryl-substituted compounds as thus defined-it is found that, for the purposes of this invention, the aryl radicals or nuclei may contain one or more substituents typically hydrocarbon radicals but more especially the monovalent alkyl hydrocarbon radicals, such as the methyl radical in the phenyl tolyl andditolyl nitroso-amines for example.

In a representative example of the invention rubber and the usual vulcanizing and filler materials, with or without an accelerator, and the required amount of the aging or anti-oxidant, reagent may be compounded and mixed in the usual way as by milling, and s subsequently molded and vulcanized to the Application filed June 4, 1929. Serial No. 368,438.

desired cure, as by heating to the usual range of vulcanization temperatures.

In a typical application of the invention, under theusual vulcanizing procedure, rubber compounds were prepared as follows:

100 parts rubber 40.5 parts carbon black 5.0 parts ZnO 3.0 parts sulphur 5 0 parts mineral rubber 3.0 parts stearic acid 8 part mercapto benzo thiazole Same as Formula I with addition of 1.0 part diphenyl nitroso-amine.

' III Same as Formula I with addition of 0.75, part diphenyl nitroso-amine.

Same as Formula I with addition of 0.50 part diphenyl nitroso-amine.

These compounds were severally mixed, as by milling in the usual manner, and then molded in thin sheets in a vulcanizing mold and vulcanized at 20 lbs. steam ressure. Samples of each compound were t us vulcanized for periods of 30, 4:5, and 60 minutes, respectively. One portion (or more) of each.

sample was then subjected to a tensile strength test, the results being given in the row indi cated by the letter A in the following table; and another portion was subjected to an oxygen aging test of 48 hours in an oxygen bomb at 70 .C. and a pressure of 300 lbs. per square inch of oxygen and then subjected to the tensile strength test, the results being given in the corresponding row indicated by B in the table.

Table I Table II-Continued Cure at twenty pounds steam pressure Cure Final 30 Minutes Final tensile Stock P d 300% 500% lbs. per 130mg oun sq. m. on--1n Final Frna 1 M111- 3007 5007 tensile elongaper cent 0 lbs. per tion in I W cent 00 20 740 2010 3335 000 00 20 737 2110 3535 005 I A 735 1905 3400 005 3,8 33 2020 $1 3 2: 3 B 784 1856 2690 635 g5 33 343 238 3350 70 H A 300 1140 2120 075 2 20 322 22 2 93? B 400 1090 1705 625 75 20 050 2200 37 00 000 m i A 583 1515 2955 680 & 3,3 23$ 23% 2 3 1 2 4 B 017 1010 2410 035 a 23 32 6 2 8 &8 2:3 I A 037 1020 3100 005 IV B 665 1675 2780 675 Aged 48 hrs. at 70 C. with 300 lbs. oxygen pressure 45 Minutes 00 715 1400 1500 510 00 20 015 2100 3050 040 Final Final 60 20 840 1920 2365 585 20 tensile elonga. 00 20 702 1020 1905 570 300% 500% lbs. per tion in 5 20 812 1550 n 5 sq per cent 75 20 000 2370 3100 020 1 1 75 20 1075 2150 2520 505 I A 950 2420' 4050 070 75 20 037 1770 2020 505 B 055 2005 2010 030 00 20 010 1500 430 00 20 1050 2400 3040 595 A I 712 2000 3420 000 90 20 1100 2245 2520 500 II 00 20 900 1000 1075 520 m A 040 2440 4125 075 Table 11 B 910 2200 3305 005 W i A 910 2500 4150 075 A B C D B 935 655 Smoked sheets 100 100 100 100 Carbon black. 40 40 4O 40 0 Minum Mmeral rubber 5 5 5 5 nxida 5 5 5 g \u' 3 3 3 3 ;g Stearic acid 3 3 3 3 300% 500% lbs tion in -*M ercapto b01120 thiazole 0. 8 0.8 0v 8 0.8 per cent Dxbeta naphthyl nitroso-amine 0 0. 75 0 0 Phenyl beta naphthyl nitros0 amine 0 0 -0. 75 0 A 1105 2330 40 0 040 Phenyl alpha naphthyl nitroso- I amme 0 0 0 0.75

n A w 4150 E 055 m1 M B 972 Z380 3455 655 tensile elo stock 300% 500% lbs. r tion in m {A 1135 2000 4175 035 Min ga g sq. 11. per cent A 1120 2930 4280 625 00 20 090 1905 3590 710 IV 00 20 030 2240 4000 700 B 1120 2520 3200 015 00 20 702 2100 3700 700 00 20 007 1005 3200 055 '1111'13 1 75 20 050 2200 3000 700 S 1 1 Vu camzlng expelulpents Wen 0111' 75 867 2360 3850 650 med out .wlth rubber composltmns contamm 75 20 900 2305 3340 005 other mtr so-ammes, mcludmg both hke an 75 unhke substltuents and hydrocarbon radicals 3% g 5% g? of both the ahphatlc and aromatlc serles. g 20 905 2% w 322 The experlmental results thus obtamed are 2 sent in th followin tables: 55 pre ed 6 T m 1% Aged 48 hrs at C. with 300 lbs. oxygen pressure 00 20 040 1450 1725 545 A B c D 00 20 090 2000 2905 030 00 20 010 1955 2030 050 00 20 705 1030 2700 040 k h 100 100 100 100 smo eds ms 40 40 40 40 20 750 1530 1030 510 5 5 5 5 75 20 914 2230 010 5 -5 5 5 75 20 075 2240 3120 045 Bulf 3 3 3 3 75 20 m 2140 3120 040 0200:1050 3 3 3 3 Mares to be 0.0 0. 0 0,0 0. 0 20 009 1520,- 400 Phanyfbetanabhthyl nitroso-amine 0 0. 75 0 0 90 20 1045 2 00 630 Benzylphony nitmso-amine 0 0 0.75 0 90 20 095 2275 3035 005 5 Carbazola nitroso-amineJ. 0 1 0 0 0.75 90 20 1030 2300 3080 615 Table IV A B O D 100 100 100 100 40 40 40 40 5 5 5 5 5 5 5 5 ur 3 3 3 3 Steal-1c acid 3 8 3 3 Mercapto benzo thlarole.-. 0. 8 0. 8 0. 8 0. 8 Diethyl nltroso-amlne. 0. 75 0 0 Plperldlne nitroso-amlne. 0 0 0. 75 0 Methyl phenyl ultimo-amine"... 0 0 0 0. 75

Curb t1511131 {final as e e engastock Mm Pounds 300% 500% lbs. ger tion in pressure sq. per cent 75 2) 780 2120 8630 680 75 M N 2430 3860 055 75 no 1055 2820 4220 640 75 I) 000 2400 3040 656 90 I) 922 2440 3970 070 00 1) N2 2610 3910 640 00 N 1168 2000 4160 630 90 1120 2825 4120 630 Aged 48 ha. at 70 0. with 300 lbl oxygen pressure 00 I) 748 1670 2100 585 50 I) 810 1825 M0 530 50 N 875 1970 2300 580 50 II) 788 1870 2490 N0 75 I) 893 1885 2170 540 75 i) 868 '1856 2245 570 75 2o 1N0 2140 2360 550 75 no 1000 2700 480 90 1) one 1900 2125 535 90 3) 933 1915 2145 545 00 a0 1018 2000 2110 510 90 I) 11185 2170 535 Table V A B 0 D Smoked sheets 100 100 100 100 Carbon black..- 40 40 40 Mineral rub 5 5 4 5 5 Zinc ox1de..-. 5 5 5 5 Sullur 3 3 3 3 Steeric 3 3 3 3 Meraipto Manolo 0. 8 0. 8 0. 8 0. 8 Dialpha nephthyl nltroeo-emlnen 0 0. 75 0 0 Phenyl ortho tolyl nitroeo'amlne. 0 0 0. 75 0 Dltolyl nltroeo-amlne 0 0 0 0. 75

Cure Final final tensile e onga- Sm Mm Poundzk 300% m lbs. tlon in pressure sq. per cent 90 20 1040 2560 4120 s15 00 Z) 1050 2680 4000 635 90 2) B0 2720 4010 645 00 20 1050 2670 3820 625 Aged 48 hrs. at 70 0. with 300 lbs. oxygen preuure I!) 000 M5 $50 630 75 Z) 930 2245 3307 630 75 20 072 2310 3410 645 75 20 972 2235 3330 650 an ass 2160 moo 620 90 20 980 2375 3380 635 90 20 1120 2500 3575 645 90 20 1060 2460 3380 035 From the data thus obtained, it is clear that the vulcanized products containing a substituted nitroso-amine exhibit a greatly improved resistance to aging or oxidation as indicated by the oxygen bomb treatment, both withrespect to intermediate and final elongation values, than the products to which such addition has not been made.

This compound is not strictly in the same category with the other compounds tested, and shows but very little improvement in the aging properties of rubber products containing it. The results are given, however, because it is related to the other nitroso-compounds. Its failure to be effective may be attributed to the valence linka e between groups corresponding to the R an R groups of the nitroso-amine which will be apparent from the formula above given.

While the above disclosure relates to preferred instances of the application of the invention and to specific reagents employed in specific proportions, it is to be understood that variations may be made therein andin the nature and amount of the several reagents used, according to'the particular requirements of the product, as will be clear to those skilled in the art of treating rubber.

Iclaim:

1. A rubber product which has been vulcanized in the presence of a diaryl substituted nitroso-amine characterized b containing a methyl substituent in the ary nucleus.

2. A rubber product which has been vulcanizedinthe presence of phenyltolyl nitrosoamine.

3. A' rubber product which has been vulcanized in the presence of phenylorthotolyl mtroso-amine.

Signed by me at Boston, Massachusetts, this 24th day of May, 1929.

MAX H. ZIMMERMANN. 

